1. Field of the Invention
The present invention relates to a breather device of an engine.
2. Related Art
In an engine of a vehicle, for example, a motorcycle, a gas accompanying a pressure generated within a cylinder bore leaks out into a crankcase little by little through a gap between a piston and the cylinder bore. Further, since the pressure of the gas within the crankcase always changes in correspondence to a sliding motion of the piston, the pressure of the gas, so-called a blowby gas within the crankcase, in a sealed state, prevents the motion of the piston. Accordingly, it is necessary to provide a means for separating a spray-like (sprayed) oil component (an oil mist) mixed in the blowby gas from a gas component as well as releasing the pressure within the crankcase to an external portion, that is, a breather device.
In order to improve a gas-liquid separating performance of the oil component in the blowby gas, it is desirable to increase a capacity of a breather chamber constituting the breather device, and to form an inner side of the breather chamber in a labyrinth structure.
As an example of a specific structure of the breather device, there is a structure in which a PCV chamber (corresponding to the breather chamber) having a plurality of baffle plates arranged in a zigzag manner in an inner portion thereof is arranged on an engine, and an expansion chamber within the crankcase and the PCV chamber are connected by a suction tube, for example, shown in Japanese Patent Laid-Open (KOKAI) Publication No. SHO 61-118521.
As shown in Japanese Utility Model Laid-Open (KOKAI) Publication No. HEI 2-46012, there is a structure in which a balance gear chamber is formed in one side of the engine by a crankcase and a gear cover connected to the crankcase via a gasket, a breather chamber sectioned by the gasket is formed in the crankcase and the gear cover, and the breather chamber and the balancer gear chamber are communicated through a breather passage.
Recently, an atmospheric pollution is prevented by reflowing the blowby gas to an air cleaner for reburning.
However, in the breather device described in Japanese Patent Laid-Open Publication No. SHO 61-118521, since the breather chamber is provided separately from the engine and is connected thereto by means of suction tube, the number of parts and assembling steps are increased, which causes a cost increase.